overhead tank over flow

[vincentsuen]

I suspect my overhead tank in the loft overflow is caused by the water come from the hot water tank's expansion pipe.
In what condition, the water will come from the hot water tank? and how can I repair it. Thanks

 

[Armo74]

The larger of the possible 2 cwsc in your loft will be for your hot water tank.I would suspect that the overflow is due to a faulty ballcock valve instead of the vent pipe unless the water in your cwsc is warm.

 

[harryfox121]

check to see if the ballvalve is leaking/dripping. then if not, is the big tank's water level higher than your small tank's level?